Auto merge of #54743 - ljedrz:cleanup_ty_p2, r=zackmdavis

[rust.git] / src / librustc / ty / mod.rs

diff --git a/src/librustc/ty/mod.rs b/src/librustc/ty/mod.rs
index 41db7c5f0390fceb49854db01533fbaaab05cd9e..2e8734a6aa8ebf730e5979b8ed7a40a0f65a7dd8 100644 (file)
--- a/src/librustc/ty/mod.rs
+++ b/src/librustc/ty/mod.rs
@@ -94,6 +94,7 @@
 pub mod cast;
 #[macro_use]
 pub mod codec;
+mod constness;
 pub mod error;
 mod erase_regions;
 pub mod fast_reject;
@@ -1476,18 +1477,17 @@ pub fn is_empty(&self) -> bool {
 /// region `'a` is in a subuniverse U2 of U1, because we can name it
 /// inside the fn type but not outside.
 ///
-/// Universes are related to **skolemization** -- which is a way of
-/// doing type- and trait-checking around these "forall" binders (also
-/// called **universal quantification**). The idea is that when, in
-/// the body of `bar`, we refer to `T` as a type, we aren't referring
-/// to any type in particular, but rather a kind of "fresh" type that
-/// is distinct from all other types we have actually declared. This
-/// is called a **skolemized** type, and we use universes to talk
-/// about this. In other words, a type name in universe 0 always
-/// corresponds to some "ground" type that the user declared, but a
-/// type name in a non-zero universe is a skolemized type -- an
-/// idealized representative of "types in general" that we use for
-/// checking generic functions.
+/// Universes are used to do type- and trait-checking around these
+/// "forall" binders (also called **universal quantification**). The
+/// idea is that when, in the body of `bar`, we refer to `T` as a
+/// type, we aren't referring to any type in particular, but rather a
+/// kind of "fresh" type that is distinct from all other types we have
+/// actually declared. This is called a **placeholder** type, and we
+/// use universes to talk about this. In other words, a type name in
+/// universe 0 always corresponds to some "ground" type that the user
+/// declared, but a type name in a non-zero universe is a placeholder
+/// type -- an idealized representative of "types in general" that we
+/// use for checking generic functions.
 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
 pub struct UniverseIndex(u32);
 
@@ -1550,6 +1550,18 @@ fn from(index: u32) -> Self {
     }
 }
 
+/// The "placeholder index" fully defines a placeholder region.
+/// Placeholder regions are identified by both a **universe** as well
+/// as a "bound-region" within that universe. The `bound_region` is
+/// basically a name -- distinct bound regions within the same
+/// universe are just two regions with an unknown relationship to one
+/// another.
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
+pub struct Placeholder {
+    pub universe: UniverseIndex,
+    pub name: BoundRegion,
+}
+
 /// When type checking, we use the `ParamEnv` to track
 /// details about the set of where-clauses that are in scope at this
 /// particular point.
@@ -1692,9 +1704,13 @@ pub struct AdtFlags: u32 {
         const IS_FUNDAMENTAL      = 1 << 2;
         const IS_UNION            = 1 << 3;
         const IS_BOX              = 1 << 4;
+        /// Indicates whether the type is an `Arc`.
+        const IS_ARC              = 1 << 5;
+        /// Indicates whether the type is an `Rc`.
+        const IS_RC               = 1 << 6;
         /// Indicates whether the variant list of this ADT is `#[non_exhaustive]`.
         /// (i.e., this flag is never set unless this ADT is an enum).
-        const IS_VARIANT_LIST_NON_EXHAUSTIVE   = 1 << 5;
+        const IS_VARIANT_LIST_NON_EXHAUSTIVE   = 1 << 7;
     }
 }
 
@@ -2014,6 +2030,12 @@ fn new(tcx: TyCtxt<'_, '_, '_>,
         if Some(did) == tcx.lang_items().owned_box() {
             flags = flags | AdtFlags::IS_BOX;
         }
+        if Some(did) == tcx.lang_items().arc() {
+            flags = flags | AdtFlags::IS_ARC;
+        }
+        if Some(did) == tcx.lang_items().rc() {
+            flags = flags | AdtFlags::IS_RC;
+        }
         if kind == AdtKind::Enum && tcx.has_attr(did, "non_exhaustive") {
             debug!("found non-exhaustive variant list for {:?}", did);
             flags = flags | AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE;
@@ -2092,6 +2114,16 @@ pub fn is_phantom_data(&self) -> bool {
         self.flags.intersects(AdtFlags::IS_PHANTOM_DATA)
     }
 
+    /// Returns `true` if this is `Arc<T>`.
+    pub fn is_arc(&self) -> bool {
+        self.flags.intersects(AdtFlags::IS_ARC)
+    }
+
+    /// Returns `true` if this is `Rc<T>`.
+    pub fn is_rc(&self) -> bool {
+        self.flags.intersects(AdtFlags::IS_RC)
+    }
+
     /// Returns true if this is Box<T>.
     #[inline]
     pub fn is_box(&self) -> bool {
@@ -2337,6 +2369,8 @@ fn sized_constraint_for_ty(&self,
                 vec![ty]
             }
 
+            UnnormalizedProjection(..) => bug!("only used with chalk-engine"),
+
             Param(..) => {
                 // perf hack: if there is a `T: Sized` bound, then
                 // we know that `T` is Sized and do not need to check
@@ -3052,6 +3086,7 @@ pub fn provide(providers: &mut ty::query::Providers<'_>) {
     erase_regions::provide(providers);
     layout::provide(providers);
     util::provide(providers);
+    constness::provide(providers);
     *providers = ty::query::Providers {
         associated_item,
         associated_item_def_ids,